Nos dan una palabra y teniendo en cuenta que las letras equivalen a a=0, b=1 (...) debemos hacer la suma y enviarla en menos de 5 segundos para obtener la flag
└─$ nc code.deadface.io 50000
DEADFACE gatekeeper: Let us see how good your programming skills are.
If a = 0, b = 1, c = 2, etc.. Tell me what the sum of this word is:
You have 5 seconds to give me an answer.
Your word is: attend
Too slow!! Word has been reset!
Stop wasting my time.
Connection Closed.
Solución
Escribí un script en python+3 que toma la palabra enviada, la calcula en base al valor de cada letra y la suma para enviarla. Una vez enviada nos envian la flag.
Utilice ord(letra)-ord(a) para convertir las letras a numeros empezando por a=0
from pwn import *
def sumWords(palabra):
suma=0
for i in palabra:
suma += ord(i)-(ord('a'))
return suma
p = remote('code.deadface.io', 50000)
word = p.recvlines(6)[5].split(b': ')
suma = sumWords(word[1].decode('utf'))
log.info('Word: '+ word[1].decode('utf') + ' | Sum: ' + str(suma))
p.sendline(str(suma).encode())
p.recvline()
log.info('Flag >> ' + p.recvline().decode('utf'))
p.close()
[x] Opening connection to code.deadface.io on port 50000
[x] Opening connection to code.deadface.io on port 50000: Trying 147.182.204.61
[+] Opening connection to code.deadface.io on port 50000: Done
[*] Word: serve | Sum: 64
[*] Flag >> flag{d1c037808d23acd0dc0e3b897f344571ddce4b294e742b434888b3d9f69d9944}flag{d1c037808d23acd0dc0e3b897f344571ddce4b294e742b434888b3d9f69d9944}aaflag{d1c037808d23acd0dc0e3b897f344571ddce4b294e742b434888b3d9f69d9944}
[*] Closed connection to code.deadface.io port 50000